1. Field of the Invention
The present invention relates to an optically recording medium, on which information can be optically recorded, and an apparatus for and a method of manufacturing the same.
2. Description of the Related Art
A DVD-RW (DVD-Re-recordable) disc is well known as an optically recording medium, on which information can be optically recorded. Such an optically recording medium is provided with: a groove track on which the record information is recorded; and land pre-pits (hereafter, merely referred to as xe2x80x9cpre-pitsxe2x80x9d)indicating various information, such as addresses and the like, each formed on a land track between adjacent turns of the groove track. The groove track has: a first region in which the record information is recorded; and a second region in which a predetermined data is formed as an embossed pit row to thereby prevent another data overwritten on the embossed pit row from being read out.
A reproducing apparatus for reproducing the record information from such an optically recording medium is designed such that a light spot is irradiated onto the groove track, a reflection light reflected on a reflection layer is detected by a light detector PD, and the recorded record information is accordingly read in. The size of this light spot is designed such that a part thereof is also irradiated onto the pre-pit formed adjacent to the groove track. Then, the reflection light from the disc is detected by the light detector PD to thereby read in the record information recorded on the groove and the various information such as the addresses and the like on the land track. However, the pre-pit formed on the land track in the first region is positioned close to the groove track. Thus, the pre-pit formed in the first region has a bad influence on an operation for reading a reproduction signal of the record information recorded on the groove track. So, this applicant has proposed the shape of the pre-pit that can minimize such a bad influence, in Japanese Patent Application Laid Open No. 2000-132868.
However, the groove track of the optically recording medium also includes the second region in which the embossed pit row is recorded. As described in the above-mentioned gazette, if the shape of the pre-pit in the first region is optimized so as to minimize the influence of the pre-pit on the reproduction signal, this optimization results in a problem that it is difficult to satisfy a required value of an aperture ratio ARe (i.e., ARe greater than 30%) of the pre-pit detection signal in the second region where the embossed pit row is formed, which is prescribed by a DVD-RW format. The aperture ratio ARe implies the ratio of a minimum amplitude APmin with respect to a maximum amplitude APmax in a pre-pit detection signal.
The present invention is proposed in view of the above mentioned problems. It is therefore an object of the present invention to provide an optically recording medium in which the pre-pit formed in the first region hardly has the bad influence on the reproduction signal, and it is possible to easily satisfy the required value of the aperture ratio of the pre-pit detection signal in the second region, and an apparatus for and a method of manufacturing the same.
The above object of the present invention can be achieved by an optically recording medium on which record information can be optically recorded, provided with: a substrate; a record surface formed on the substrate and having a first region where the record information is recorded and a second region where predetermined data to control recording and/or reproducing the record information is recorded; groove tracks formed in the first region and the second region, on which the record information is recorded in the first region and on which the predetermined data is recorded as an embossed pit row in the second region so as to prevent another data overwritten on the embossed pit row from being read out; a land track formed in the first region and the second region between the groove tracks adjacent to each other; and pre-pits arranged on the land track in the first region and the second region and including address information, which indicates a record position on the groove track, the pre-pit in the second region being formed in a shape different from that in the first region such that a larger amplitude of a pre-pit detection signal corresponding to the pre-pit is obtained in the second region as compared with that in the first region.
According to the optically recording medium of the present invention, the shape of the pre-pit formed in the second region is different from that in the first region, so as to obtain the larger amplitude of the pre-pit detection signal. Thus, the value of the aperture ratio ARe of the pre-pit detection signal in the second region becomes larger, which can easily satisfy the required value e.g., ARe greater than 30% which is prescribed by a DVD-RW format.
In one aspect of the optically recording medium of the present invention, the pre-pit in the first region is formed so as to minimize an influence of the pre-pit on a reproduction signal corresponding to the record information read out from the groove tracks.
According to this aspect, in the first region the influence of the pre-pit on the reproduction signal can be minimized while, in the second region, the value of the aperture ration ARe can be made certainly large.
In another aspect of the optically recording medium of the present invention, the pre-pit in the second region is formed longer in a scanning direction than the pre-pit in the first region.
According to this aspect, in the second region, it is possible to increase the value of the aperture ration ARe by virtue of the longer pre-pit formed in the second region.
In another aspect of the optically recording medium of the present invention, the pre-pit in the second region is formed deeper than the pre-pit in the first region.
According to this aspect, in the second region, it is possible to increase the value of the aperture ration ARe by virtue of the deeper pre-pit formed in the second region.
In another aspect of the optically recording medium of the present invention, the pre-pit in the second region is formed larger in a disc radial direction than the pre-pit in the first region.
According to this aspect, in the second region, it is possible to increase the value of the aperture ration ARe by virtue of the larger pre-pit formed in the second region.
In another aspect of the optically recording medium of the present invention, the second region is located at an address same as that of a region where reproduction control information of a recording medium dedicated to a reproduction is recorded.
According to this aspect, it is protect an RF (Radio Frequency) copy e.g., an RF copy to a DVD-RW disc from a DVD-ROM disc.
The above object of the present invention can be also achieved by an apparatus for manufacturing an optically recording medium, on which record information can be optically recorded, by using an original disc, provided with: a groove track forming device for forming groove tracks on a surface of the original disc, on which the record information is to be recorded in a first region and on which predetermined data to control recording and/or reproducing the record information is recorded as an embossed pit row in a second region, so as to prevent another data overwritten on the embossed pit row from being read out; and a pre-pit forming device for forming pre-pits arranged on a land track between the groove tracks adjacent to each other in the first region and the second region and including address information, which indicates a record position on the groove track, the pre-pit forming device forming the pre-pit in the second region in a shape different from that in the first region such that a larger amplitude of a pre-pit detection signal corresponding to the pre-pit is obtained in the second region as compared with that in the first region.
According to the manufacturing apparatus of the present invention, the above described optically recording medium of the present invention can be surely and easily manufactured.
In one aspect of the manufacturing apparatus of the present invention, the pre-pit forming device forms the pre-pit in the first region so as to minimize an influence of the pre-pit on a reproduction signal corresponding to the record information read out from the groove tracks.
In another aspect of the manufacturing apparatus of the present invention, the pre-pit forming device forms the pre-pit in the second region longer in a scanning direction than the pre-pit in the first region.
In another aspect of the manufacturing apparatus of the present invention, the pre-pit forming device forms the pre-pit in the second region deeper than the pre-pit in the first region.
In another aspect of the manufacturing apparatus of the present invention, the pre-pit forming device forms the pre-pit in the second region larger in a disc radial direction than the pre-pit in the first region.
In another aspect of the manufacturing apparatus of the present invention, the second region is located at an address same as that of a region where reproduction control information of a recording medium dedicated to a reproduction is recorded.
The above object of the present invention can be also achieved by a method of manufacturing an optically recording medium, on which record information can be optically recorded, by using an original disc, including: a groove track forming process of forming groove tracks on a surface of the original disc, on which the record information is to be recorded in a first region and on which predetermined data to control recording and/or reproducing the record information is recorded as an embossed pit row in a second region, so as to prevent another data overwritten on the embossed pit row from being read out; and a pre-pit forming process of forming pre-pits arranged on a land track between the groove tracks adjacent to each other in the first region and the second region and including address information, which indicates a record position on the groove track, the pre-pit forming process forming the pre-pit in the second region in a shape different from that in the first region such that a larger amplitude of a pre-pit detection signal corresponding to the pre-pit is obtained in the second region as compared with that in the first region.
According to the manufacturing method of the present invention, the above described optically recording medium of the present invention can be surely and easily manufactured.
In one aspect of the manufacturing method of the present invention, the pre-pit forming process forms the pre-pit in the first region so as to minimize an influence of the pre-pit on a reproduction signal corresponding to the record information read out from the groove tracks.
In another aspect of the manufacturing method of the present invention, the pre-pit forming process forms the pre-pit in the second region longer in a scanning direction than the pre-pit in the first region.
In another aspect of the manufacturing method of the present invention, the pre-pit forming process forms the pre-pit in the second region deeper than the pre-pit in the first region.
In another aspect of the manufacturing method of the present invention, the pre-pit forming process forms the pre-pit in the second region larger in a disc radial direction than the pre-pit in the first region.
In another aspect of the manufacturing method of the present invention, the second region is located at an address same as that of a region where reproduction control information of a recording medium dedicated to a reproduction is recorded.